Display devices such as televisions (TVs) often display both static and dynamically moving graphical objects, as do display devices such as cathode ray tubes (CRTs) and Liquid Crystal Displays (LCDs) used with Personal Computers (PCs). These moving objects will be referred to in this description as Graphical User Interface (GUI) objects. The GUI objects of interest in this description are graphical elements such as icons or animated graphics that represent certain information to the user, and whose movements or positions on the display often change continuously in various directions or at various rates.
Common pointing devices used in PC systems include the mouse, trackball and joystick, and these are used to position a cursor at a desired position on the PC display screen. For example, the cursor may be positioned in such a manner as to define an insertion point at which text is to be incorporated into a document being displayed by a word processing application running on the PC. The pointing devices, and particularly the joystick, can also be used for dynamic applications such as PC based action games in which, for example, a representation of an aeroplane can thereby be guided about the display screen.
The aforementioned pointing devices typically have a range of operation that enables the cursor to be moved about the entire expanse of the display screen, and a constant relationship is typically maintained between an operating position of the pointing device and the corresponding location of the cursor on the display screen. In highly dynamic video applications, this arrangement, however, requires a high degree of sensory-motor coordination from the typical user, who is therefore unable to easily track a desired dynamically moving object on the screen.